Calculating device



(No Model.)

W. D. F. JARVIS.

I CALCULATING DEVIQE- No. 338,075. Patented Mar. 16, 1886.

' INVENTOR .llttorney UNITED STATES PATENT FFTQE WILLIAM D. F. JARVIS,OF PHILIPPI, VEST VIRGINIA.

CALCULATING DEVICE.

FPECIFiGATZON forming part of Letters Patent No. 338,075, dated li Iarch16, 1886.

Application filed NovembcrQO, 1855. Serial No. 183,388. (No model.)

T0 at whom it may concern:

Be it known that I, VILLIAM D. F. JARVIS, of Philippi, in the county ofBarbour and State of West Virginia, have invented certain new and usefulImprovements in Calculating Devices; and I do hereby declare that thefollowing is a full, clear, and exact description thereof, referencebeing had to the accompanying drawings, and to the letters of referencemarked thereon, which form part of this specification, in which Figurelis aplan View of the device. Fig. 2 is a cross-section of the same online mm, Fig. 1.

This invention is an improved automatic calculating device forreckoning. amounts in cash for any number of days within a month orwithin an entire year; and it consists, essentially, in the novelarrangement and construction of two disks pivoted centrally to eachother and suitably scored 0r numbered on their faces adjacent to theirperipheries, so that they can be made to properly register with eachother, as hereinafter described, and pointed out in the appended claims.

The invention is especially adapted for use in hotels, in calculatingpay-rolls,or wherever certain fixed sums are to be paid by the day, thewhole amount for any number of days being readily ascertained by turningone disk upon the other, as hereinafter fully described.

In the accompanying drawings, A designates the wall, table, or othersupport to which the device is afiixed.

The device is preferably attached in such manner as to stand vertically,as shown in the drawings.

B is the device, composed mainly of the concentric disks 0 and D, bothpivoted through their centers to the support A.

d is the pivotal pin of the disks, having on its threaded outer end thenut b, which rests against the outer surface of the front and smallerdisk, D, and keeps the disks in place.

0 is an indicator, pointer, or finger secured to the support A, with itsedge e vertically below the centers of the disks and lying in a radialline of the disk 0. The front and smaller disk, D, is provided with thelugs (Z, by means of which it may be readily turned, and is constructedwithin its marked rim (1, hereinafter described, of slate or anyequivalent material capable of being marked upon, as blackboard, thelugs 11 being situated near the inner edge of the rim (1 and the disk d"of slate being seter disk graduated into thirty-one principal or primarydivisions. F, by radial lines, as shown. Each ofthe divisions F is alsograduated by radial lines into equal parts corresponding in number tothose of the thirtyone divisions of the disk D, heretofore described.The graduated portion ofthe disk 0 is scored by the concentric circlesG, G, and G from within outward, forming with the radial lines thespacesg, g, and g, arranged in circularsets. The inner set of spaces, g,running from a radial line marked 0 0, are in this instance numbered i.-3 it, and l for the first succeeding principal division, and for thesucceeding division numbered ll, 1%, 1i, and 2, and so around the disk,the last space being numbered 31, as shown. These fractions are for wantof space in the drawings indicated only by their numerators, thedenominators being in all cases 4.

The spaces 9 g are numbered as follows: The outer circle, 9*, startingfrom the nought radial line, is numbered with whole numbers, and theinner circle of spacesgflare numbered with fractions,preferably decimalsof the same. These numbers ascend in regular arithmetical ratio,starting from the 0 or zero-line. The spaces 9, for example, begin withzero (0) and increase by an arithmetical ratio of one, and run upwardfrom the zero-line from right to left, as shown in the drawings, thoughthe direction might be reversed, if desirable.

To fully understand the manner in which the two disks coaet, thefollowing description is necessary: The rim of the disk D is graduatedinto thirty-one principal divisi0ns,each of which is divided into fourequal parts in the present instance. The rim of the disk is similarlygraduated, so that when the left edge of the division 1 of theformercorresponds with the naught radial line of the latter the spacesB, D, S, and L will be opposite a line of spaces, g, g, and g", of thedisk 0. The spaces 9 are marked from the naught-line with fourths of aday, and the spaces 9 g are marked with numbers, which show a certain 1oprice by the fourth of the day, in this case fifty cents, or two dollarsfor the whole day. Now, it is evident that by putting the left edge ofthe division marked 1 of disk D above the 0 0, radial or zero line ofdisk 0, and moving both together to the left, the corresponding pricefor any number of days and fractions thereof will be in the spaces 9 gof the disk 0 immediately adjacent to the space for the number of daysor fractions thereof on the disk D.

For months of thirty days, in passing from the end of the month to someday in the next succeeding month, the outer disk, D, is set back one daydistance on the disk 0, and for the month of February it is set backthree days distance thereon, the disk D being marked for thirty-onedays. \Vhen the device is attached vertically to a wall, the edge of thedisk 0 is provided with a weight, X, so as to cause its 00 radial lineto be brought by gravity to the edge of the bracket.

Having described my invention I claim- 1. The combination of theindicating arm or finger 0, having an edge, 0, situated in a radial lineof the disk 0, the rotating disk G having its edge weighted, so as tobring by, gravity its nought radial line to correspond with the edge 0of said finger c, and the roasao'is tating disk D, pivoted through itscenter and turning concentrically on the disk 0, substano tially asspecified.

2. The combination of the support A, the indicating-finger a, securedthereto, and having an edge, 0, situated in a radial line of the disk 0,the disk D, having thirty-one equal 5 divisions around it near its edge,each division being divided into four equal parts to show the parts of aday, and the disk 0 provided with the series of divisions g g 9 near itsedge, the divisions 9 being marked from the zero-line with fourths of aday in an ascending series, and the spaces 9 g 9" being marked from thezero-line with numbers which show the corresponding prices for fourthsof a day in an ascending series, substantially as specified.

3. The combination of the support A, the indicating-finger c,securedthereto,and having an edge, e, situated in a radial line of the disk 0,the disk 0 having the .graduations, substantially as described, andprovided on its edge with the weight X, arranged to cause the disk tomove by gravity into the position in which its zero-line will correspondwith the edge a of the finger 0, and the disk D graduated, as described,on its edge, and having its surface made of some material capable ofhaving records or notes made upon it,substantially as specified.

V In testimony that I claim the foregoing as my own I atfix my signaturein presence of two witnesses.

WILLIAM D. F. JARVIS.

\Vitnesses:

GRANK E. TAFT,

I. H. ROBINSON.

